[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [PATCH] target/arm/arch_dump: Add SVE notes
From: |
Andrew Jones |
Subject: |
Re: [PATCH] target/arm/arch_dump: Add SVE notes |
Date: |
Fri, 4 Oct 2019 13:31:07 +0200 |
User-agent: |
NeoMutt/20180716 |
On Fri, Oct 04, 2019 at 11:46:09AM +0200, Andrew Jones wrote:
> When dumping a guest with dump-guest-memory also dump the SVE
> registers if they are in use.
>
> Signed-off-by: Andrew Jones <address@hidden>
> ---
> include/elf.h | 2 +
> target/arm/arch_dump.c | 133 ++++++++++++++++++++++++++++++++++++++++-
> 2 files changed, 133 insertions(+), 2 deletions(-)
>
> diff --git a/include/elf.h b/include/elf.h
> index 3501e0c8d03a..a7c357af74ca 100644
> --- a/include/elf.h
> +++ b/include/elf.h
> @@ -1650,6 +1650,8 @@ typedef struct elf64_shdr {
> #define NT_ARM_HW_BREAK 0x402 /* ARM hardware breakpoint registers
> */
> #define NT_ARM_HW_WATCH 0x403 /* ARM hardware watchpoint registers
> */
> #define NT_ARM_SYSTEM_CALL 0x404 /* ARM system call number */
> +#define NT_ARM_SVE 0x405 /* ARM Scalable Vector Extension
> + registers */
>
> /*
> * Physical entry point into the kernel.
> diff --git a/target/arm/arch_dump.c b/target/arm/arch_dump.c
> index 26a2c098687c..98976167d155 100644
> --- a/target/arm/arch_dump.c
> +++ b/target/arm/arch_dump.c
> @@ -62,12 +62,23 @@ struct aarch64_user_vfp_state {
>
> QEMU_BUILD_BUG_ON(sizeof(struct aarch64_user_vfp_state) != 528);
>
> +/* struct user_sve_header from arch/arm64/include/uapi/asm/ptrace.h */
> +struct aarch64_user_sve_header {
> + uint32_t size;
> + uint32_t max_size;
> + uint16_t vl;
> + uint16_t max_vl;
> + uint16_t flags;
> + uint16_t reserved;
> +} QEMU_PACKED;
> +
> struct aarch64_note {
> Elf64_Nhdr hdr;
> char name[8]; /* align_up(sizeof("CORE"), 4) */
> union {
> struct aarch64_elf_prstatus prstatus;
> struct aarch64_user_vfp_state vfp;
> + struct aarch64_user_sve_header sve;
> };
> } QEMU_PACKED;
>
> @@ -76,6 +87,8 @@ struct aarch64_note {
> (AARCH64_NOTE_HEADER_SIZE + sizeof(struct aarch64_elf_prstatus))
> #define AARCH64_PRFPREG_NOTE_SIZE \
> (AARCH64_NOTE_HEADER_SIZE + sizeof(struct
> aarch64_user_vfp_state))
> +#define AARCH64_SVE_NOTE_SIZE(env) \
> + (AARCH64_NOTE_HEADER_SIZE + sve_size(env))
>
> static void aarch64_note_init(struct aarch64_note *note, DumpState *s,
> const char *name, Elf64_Word namesz,
> @@ -128,11 +141,111 @@ static int
> aarch64_write_elf64_prfpreg(WriteCoreDumpFunction f,
> return 0;
> }
>
> +#ifdef TARGET_AARCH64
> +static off_t sve_zreg_offset(uint32_t vq, int n)
> +{
> + off_t off = sizeof(struct aarch64_user_sve_header);
> + return ROUND_UP(off, 16) + vq * 16 * n;
> +}
> +static off_t sve_preg_offset(uint32_t vq, int n)
> +{
> + return sve_zreg_offset(vq, 32) + vq * 16 / 8 * n;
> +}
> +static off_t sve_fpsr_offset(uint32_t vq)
> +{
> + off_t off = sve_preg_offset(vq, 17) + offsetof(struct aarch64_note, sve);
> + return ROUND_UP(off, 16) - offsetof(struct aarch64_note, sve);
> +}
> +static off_t sve_fpcr_offset(uint32_t vq)
> +{
> + return sve_fpsr_offset(vq) + sizeof(uint32_t);
> +}
> +static uint32_t sve_current_vq(CPUARMState *env)
> +{
> + return sve_zcr_len_for_el(env, arm_current_el(env)) + 1;
> +}
> +static size_t sve_size(CPUARMState *env)
> +{
> + off_t off = sve_fpcr_offset(sve_current_vq(env)) +
> + sizeof(uint32_t) +
> + offsetof(struct aarch64_note, sve);
> + return ROUND_UP(off, 16) - offsetof(struct aarch64_note, sve);
> +}
> +
> +static int aarch64_write_elf64_sve(WriteCoreDumpFunction f,
> + CPUARMState *env, int cpuid,
> + DumpState *s)
> +{
> + struct aarch64_note *note;
> + uint32_t vq = sve_current_vq(env);
> + uint32_t fpr;
> + uint8_t *buf;
> + size_t size;
> + int ret, i;
> +
> + note = g_malloc0(AARCH64_SVE_NOTE_SIZE(env));
> + size = sve_size(env);
> + buf = (uint8_t *)¬e->sve;
> +
> + aarch64_note_init(note, s, "LINUX", 6, NT_ARM_SVE, size);
> +
> + note->sve.size = cpu_to_dump32(s, size);
> + note->sve.max_size = cpu_to_dump32(s, size);
Oops. I seemed to have mixed two approaches to this note.
Approach 1) do what gcore does
Approach 2) do what section 8 "ELF coredump extensions" of Linux kernel
doc Documentation/arm64/sve.rst says to do
Approach 2 says the contents of this note should be equivalent to what
would have been read with ptrace. However Approach 1 has it's own idea
of what to provide in the note. Namely it uses the current vl size for
both 'size' and 'max_size', as I've done above, and it doesn't provide
FPSR and FPCR in the SVE note, which I did provide below. But if you do a
ptrace then you'll see FPSR and FPCR should be provided and the max_size
is necessarily reflective of the max, as ptrace may be called multiple
times - whereas with a core it doesn't really matter.
I'll post a v2 that implements Approach 2, because that's the documented
way to do it. I'm open to arguments for Approach 1 though.
Thanks,
drew
> + note->sve.vl = cpu_to_dump16(s, vq * 16);
> + note->sve.max_vl = cpu_to_dump16(s, vq * 16);
> + note->sve.flags = cpu_to_dump16(s, 1);
> +
> + for (i = 0; i < 32; ++i) {
> +#ifdef HOST_WORDS_BIGENDIAN
> + uint64_t d[vq * 2];
> + int j;
> +
> + for (j = 0; j < vq * 2; ++j) {
> + d[j] = bswap64(env->vfp.zregs[i].d[j]);
> + }
> +#else
> + uint64_t *d = &env->vfp.zregs[i].d[0];
> +#endif
> + memcpy(&buf[sve_zreg_offset(vq, i)], &d[0], vq * 16);
> + }
> +
> + for (i = 0; i < 17; ++i) {
> +#ifdef HOST_WORDS_BIGENDIAN
> + uint64_t d[DIV_ROUND_UP(vq * 2, 8)];
> + int j;
> +
> + for (j = 0; j < DIV_ROUND_UP(vq * 2, 8); ++j) {
> + d[j] = bswap64(env->vfp.pregs[i].p[j]);
> + }
> +#else
> + uint64_t *d = &env->vfp.pregs[i].p[0];
> +#endif
> + memcpy(&buf[sve_preg_offset(vq, i)], &d[0], vq * 16 / 8);
> + }
> +
> + fpr = cpu_to_dump32(s, vfp_get_fpsr(env));
> + memcpy(&buf[sve_fpsr_offset(vq)], &fpr, sizeof(uint32_t));
> +
> + fpr = cpu_to_dump32(s, vfp_get_fpcr(env));
> + memcpy(&buf[sve_fpcr_offset(vq)], &fpr, sizeof(uint32_t));
> +
> + ret = f(note, AARCH64_SVE_NOTE_SIZE(env), s);
> + g_free(note);
> +
> + if (ret < 0) {
> + return -1;
> + }
> +
> + return 0;
> +}
> +#endif
> +
> int arm_cpu_write_elf64_note(WriteCoreDumpFunction f, CPUState *cs,
> int cpuid, void *opaque)
> {
> struct aarch64_note note;
> - CPUARMState *env = &ARM_CPU(cs)->env;
> + ARMCPU *cpu = ARM_CPU(cs);
> + CPUARMState *env = &cpu->env;
> DumpState *s = opaque;
> uint64_t pstate, sp;
> int ret, i;
> @@ -163,7 +276,18 @@ int arm_cpu_write_elf64_note(WriteCoreDumpFunction f,
> CPUState *cs,
> return -1;
> }
>
> - return aarch64_write_elf64_prfpreg(f, env, cpuid, s);
> + ret = aarch64_write_elf64_prfpreg(f, env, cpuid, s);
> + if (ret) {
> + return ret;
> + }
> +
> +#ifdef TARGET_AARCH64
> + if (cpu_isar_feature(aa64_sve, cpu)) {
> + ret = aarch64_write_elf64_sve(f, env, cpuid, s);
> + }
> +#endif
> +
> + return ret;
> }
>
> /* struct pt_regs from arch/arm/include/asm/ptrace.h */
> @@ -335,6 +459,11 @@ ssize_t cpu_get_note_size(int class, int machine, int
> nr_cpus)
> if (class == ELFCLASS64) {
> note_size = AARCH64_PRSTATUS_NOTE_SIZE;
> note_size += AARCH64_PRFPREG_NOTE_SIZE;
> +#ifdef TARGET_AARCH64
> + if (cpu_isar_feature(aa64_sve, cpu)) {
> + note_size += AARCH64_SVE_NOTE_SIZE(env);
> + }
> +#endif
> } else {
> note_size = ARM_PRSTATUS_NOTE_SIZE;
> if (arm_feature(env, ARM_FEATURE_VFP)) {
> --
> 2.20.1
>